1. Field of the Invention
The present invention relates to a process for the production of poly(4-hydroxystyrene) (PHS) directly from 4-hydroxyphenylmethylcarbinol (HPMC) which in turn is prepared from 4-hydroxyacetophenone (4-HAP).
2. Description of the Prior Art
It is known in the art to produce 4-hydroxystyrene (HSM) and derivatives thereof such as poly(4-hydroxystyrene) (PHS), which have applications in the production of adhesives, coating compositions, photoresists, and the like. In the PHS area, there is a need to produce such material in the least amount of process steps in order to provide efficiency. The prior art has utilized a five-step process in order to produce PHS. We have now found that PHS can be produced in three steps or less.
In the past, one of the ways of preparing poly(4-hydroxystyrene) (PHS) was the use of 4-hydroxystyrene (HSM) as the starting material; note European Patent Application No. 0-108-624. 4-Hydroxystyrene (HSM) is a well-known compound in the art.
Although there are several known ways to prepare 4-hydroxystyrene, these known methods are not commercially feasible in the further utilization of the 4-hydroxystyrene. The 4-hydroxystyrene itself is difficult to isolate, since it (1) readily decomposes, and (2) is toxic via skin absorption, and, as a result, those skilled in the art have made numerous attempts at finding a method of synthesizing PHS in a manner which avoids using the 4-hydroxystyrene as the starting material.
The following prior art references are disclosed in accordance with the terms of 37 CFR 1.56, 1.97, and 1.93.
U.S. Pat. No. 5,087,772 (issued Feb. 11, 1992) discloses the preparation of HSM by reacting 4-acetoxystyrene (ASM) with a suitable alcohol in the presence of a catalytic amount of a suitable base.
European Patent Application No. 0-128-984 (publication no.), filed Aug. 30, 1983, discloses a process for the production of para-vinyl phenol (HSM) by dehydrogenation of para-ethyl phenol.
European Patent Application No. 0-108-624 (publication no.), filed Nov. 4, 1983, discloses a process for the production of p-vinyl phenol polymer (polyhydroxystyrene polymer--PHS) by polymerizing p-vinyl phenol (HSM) in the presence of water and iron.
U.S. Pat. No. 4,032,513 (issued Jun. 28, 1977) discloses a process of producing PHS by cationically polymerizing HSM in the presence of a nitrile, such as CH.sub.3 CN, using a cationic polymerization initiator in a homogeneous reaction system.
U.S. Pat. No. 5,041,614 discloses a method for the preparation of 4-acetoxystyrene (ASM) from 4-acetoxyphenylmethylcarbinol. (Note Formula I for the structural formula for ASM).
U.S. Pat. No. 5,084,533 discloses a process for the neat hydrogenation of 4-acetoxyacetophenone in the production of 4-acetoxystyrene (ASM).
U.S. Pat. No. 5,151,546 discloses a process for preparing 4-acetoxystyrene (ASM) by heating 4-acetoxyphenylmethylcarbinol with an acid catalyst.
U.S. Pat. No. 5,245,074 discloses a process for preparing 4-acetoxystyrene (ASM) through the 4-acetoxyacetophenone/4-acetoxyphenylmethylcarbinol route.
U.S. Pat. No. 5,247,124 discloses a process for preparing substituted styrenes such as ASM by reacting a bisarylalkyl ether in the presence of an acid catalyst.
J. Org. Chem., (1954), 19, 1205, discloses the use of copper chromite catalysts in the hydrogenation of ketones.
Other prior art references which relate to the present invention include U.S. Pat. No. 2,276,138; U.S. Pat. No. 3,547,858; U.S. Pat. No. 4,544,704; U.S. Pat. No. 4,678,843; U.S. Pat. No. 4,689,371; U.S. Pat. No. 4,822,862; U.S. Pat. No. 4,857,601; U.S. Pat. No. 4,868,256; U.S. Pat. No. 4,877,843; U.S. Pat. No. 4,898,916; U.S. Pat. No. 4,912,173; U.S. Pat. No. 4,962,147; U.S. Pat. No. 4,965,400; U.S. Pat. No. 4,880,487; U.S. Pat. No. 5,264,528; U.S. Pat. No. 5,342,727; and Reissue U.S. Pat. No. 34, 122.
All of the above-cited prior art and any other references mentioned herein are incorporated herein by reference in their entirety.